Fungicidal lacquer



FUNGICIDAL LACQUER Walter S. Osborne, Sumter, S. C.

No Drawing. Application September 6, 1945, Serial No. 614,801

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 6 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to fungicidal coating compositions and is especially directed toward the method of employing such compositions for killing living fungous growths of all kinds and the inhibition of such growths on the surfaces and interiors of articles, instruments and equipment made of metals, plastics, textiles, leather, wood and other materials, in damp climates. A particular object is to provide a fungicide lacquer which is especially useful in manufacturing insulation for electrical equipment, wiring etc., since it will withstand baking. Still another is to provide a fungicide lacquer having definite anti-corrosion characteristics. A further object is to provide a fungicide which may be mixed with anticorrosion compounds and oi s, as well as alcohol, to form mixtures useful for various purpdslas to be described. Other objects will be apparent from the following description of the invention.

My invention differs from the above and other known prior art in that it is a fungicide lacquer consisting of a mixture of two chemical compounds, viz., ortho-cresyl-azo-diamino-benzene hydrochloride, and tetra brome ortho-cresol, both of which are crystalline powders, soluble in either alcohol or water. The preferred embodiment of the invention consists of a major proportion of a clear lacquer to which is added a fungicide consisting of 80% by weight of orthocresyl-azo-diamino-benzene hydrochloride and 20% by weight of tetra-bromo-ortho-creso1 in substantial amount. The fungicidal powder when dissolved forms a clear, slightly pungent, red or brown liquid, depending upon solvent employed, and is a powerful fungicide which may be incorporated by known methods in many oils, waxes, resins, plastics, detergents etc. as well as in varnishes, lacquers and dyes. Generally speaking the 80-20 mixture mentioned above is most satisfactory, but I may employ as much as 95% of the ortho-cresyl-azo-diamino benzene hydrochloride, or as little as 5% to make the fungicidal base intended for dissolution in a vehicle.

In accordance with rules prescribed by the National Defense Research Committee, Washington, D. 0., tests were conducted as follows: A one inch strip of insulated electrical wire, previously untreated with a fungicide, was dipped into clear melamine lacquer containing 2.2 by weight of the above 80-20 mixture. Then the test speccooling to room temperature a spore suspension spray of aspcrgzllus m'ger, aspcrgillus flcmus, pencillz'um Zuteum and trichoderma T-l (all tropical fungi) was applied. Next the specimen was put in a Petri dish containing nutrient agar and then placed in a fungus chamber maintained at a constant temperature of F.i5 and relative humidity of -100%. On the fifth day, the specimen was removed, reinoculated with the same spray, and replaced in the chamber and allowed to remain for sixty days, with daily observations under a 20 power microscope. The described fungicide formed a complete protective coating and apparently killed or warded off all spores from surrounding fungi and moisture. As it has been established that two weeks of such an accelerated test are the equivalent of sixteen weeks in the tropics for some articles, an acceleration ratio of 8:1 for some types of material, it is considered that the sixty days of the test were the equivalent of 480 days in the tropics.

The combination of the two ingredients mentioned above produces a result which either ingredient used alone cannot effect. Tetra-bromoortho-cresol if employed alone shows definite skin irritant properties, while the mixture does not irritate the skin. The mixture gives more lasting fungicidal effects than either ingredient used alone, and seemingly is a more powerful agent than either ingredient used without the other. Furthermore, the mixture displays water repellant properties when mixed with clear lacquer, varnishes, etc. which are applied to various electrical equipment and apparatus for the purpose of inhibiting fungus growth on their surfaces.

The described fungicide lacquer is especially useful for the treatment of electrical apparatus, radios and in general all insulation which is subject to attack by fungi. It is particularly adapted to withstand baking at moderate temperatures (at least 250 F.) without loss of its fungicidal power.

The amount of the fungicide mixture which is to be dissolved in the clear lacquer (commercial or Government grade) will be governed by the use to which the lacquer will be put. Generally 2.2% by weight of solids in the lacquer will be found sufficient. Either the 95-5% mixture or the 80-20% mixture may be so proportioned in a vehicle such as a lacquer, varnish, or wax. It is preferred that the vehicle have good electrical insulating properties. More or less of the fungicide may be dissolved in the vehicle than the 2.2% by weight of solids in the lacquer disclosed so imen was dried at 255 F. for one hour, and after 55 lon as thmamnnai i t and does not SEARCH RdQti interfere with the applicability of the finished composition by spraying or brushing or dipping.

Having described the invention, what I claim as new and desire to secure by Letters Patent is:

1. A fungus-inhibiting lacquer comprising a substantial proportion of a fungicide consisting of -95% by weight of ortho-cresyl-azo-diamino benzene hydrochloride, and '95-5% by weight of tetra-bromo-ortho-cresol and a larger proportion of clear lacquer.

2. A fungus-inhibiting lacquer comprising a substantial proportion of a fungicide consisting of 80% 'by weight of ortho-cresyl-azo-diaminobenzene hydrochloride and 20% by weight of tetra-bromo-ortho-cresol and a larger proportion of clear lacquer. I

3. A lacquer capable of inhibiting the growth of fungi on surfaces to which it has been applied, said lacquer comprising a major proportion of commercial clear lacquer and a minor but substantial proportion of a fungicide comprising ortho-cresyl-azo-diamino benzene hydrochloride and. tetra-bromo-ortho-cresol.

4. A lacquer according to claim 3 in which the commercial lacquer present in major proportion is a melamine lacquer.

5. A lacquer according to claim 3 in which the minor proportion of fungicide present amounts to about 2.2% by weight of solids in the lacquer.

6. A lacquer according to claim 3 in which the minor proportion of fungicide present amounts to about 2.2% by weight of solids in the lacquer and the commercial clear lacquer is a melamine lacquer.

WALTER S. OSBORNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,053,095 Maximoff Sept. 1, 1936 2,318,121 Widmer May 4, 1943 2,347,635 Smith Apr. 25, 944 2,434,291 Smith Jan. 13, 1948 OTHER REFERENCES Gutman, Modern Drug Encyclopedia and Therapeutic Index, page 92, Yorke Pub. Co., Inc., N. Y. 1946. 

